This project has been under study for 18 months. Two avenues of research are being investigated in order to clarify the etiology and incidence of cerebral fat emboli: Neuropathological studies have indicated a 22 per cent incidence of cerebral fat emboli. This is a reduction from an 80 per cent incidence known to occur in 1969. Using immunofluorescent techniques, the cerebral fat is positive for both beta and alpha lipoprotein. The blood lipid chemistry has also been studied in patients undergoing clinical open heart surgery. This has shown there is an abnormality (denaturization) in the phospholipoprotein associated with extracorporeal oxygenation. This abnormality can be associated with the result of a number of variables encountered in open heart surgery. An animal model is now being developed to test these variables.